Americans are increasingly concerned with eating healthy. Over the past two decades, there has been a myriad of changes in the public’s perception of what is and isn’t healthy. Initially, it was generally agreed upon and understood that a diet consisting mainly of greasy food and too much sweets was unhealthy. However, the consensus on what foods are to be considered healthy versus harmful has become complex and the subject of much debate. For instance, it was once considered unhealthy to eat eggs, though the medical consensus has changed— it turns out that eggs are not as high in cholesterol as once thought—many people still maintain that the yolks should be removed, and that egg whites are healthier.

Much of the focus on health has revolved around a single nutrient, food, or food group. For example, whole wheat  became preferred over bleached flour, then eventually, eating any wheat at all became controversial and wheat-free diets were promoted. The same happened with rice: white rice gave way to brown rice, which then gave way to quinoa. Super foods like soy, kale, and chia seeds became popular, along with fad diets, like the Atkins diet which emphasized low carbohydrate intake, and the Southbeach diet. Most recently,  health gurus promoted health concepts which lead to the  alkaline diet, out of which came alkaline water. Now, sensationalized documentaries are leading people to abandon meat and dairy all together.

As a result, many are unfortunately left confounded when it comes to what they should or should not eat. There is much fear surrounding food safety and health, due impart to a lack of understanding of nutritional requirements and technological advancements in food production, leaving many weary that meat and dairy, in particular, can lead to the development of Cardiovascular disease and Type 2 Diabetes. However, focusing on the beneficial effects of a single nutrient, food, or food group does not comprise a healthy diet. What is more important is dietary pattern; the amounts, frequency, and variety of nutrients and foods that are consumed habitually, coupled with other lifestyle factors, are the greatest determinants in the association of diet and health, as Cardiovascular Disease and Diabetes are consequences of leading a sedentary lifestyle while being overweight or obese.

Cardiovascular Disease

Cardiovascular Disease is the leading cause of death for both men and woman in the United States. Many people still do not fully know or understand the etymology of Cardiovascular Disease. There are specific factors involved in the development of cardiovascular disease; though they may seem to be a list of variables, each factor ultimately causes damage to the lining of blood vessels and the heart.

The most common type of Cardiovascular Disease is Coronary Artery Disease, more commonly known as Atherosclerosis. It is a condition in which plaque builds up inside of the arteries that supply oxygenated blood to the heart, making it incapable of pumping enough blood throughout the body.  Plaque buildup narrows the artery and can either restrict or occlude the passage of blood through the vessel, increasing the risk of blood clots and subsequently, strokes.  Coronary  artery disease puts the heart under strain, causing angina , arrhythmias, and heart attack. Ultimately, heart failure occurs due to weakening of the heart muscle.

Cardiovascular disease is initiated by damage to the blood vessels. The major causes of injury to blood vessels are cigarette smoke, high amounts of certain fats, cholesterol, and sugar in the blood, as well as having high blood pressure. Making, smoking, obesity or being overweight, and Diabetes, the major risk factors for developing Cardiovascular disease. Lifestyle also plays a significant role; lack of exercise, increasing age, family history, and genetics contribute to the etymology of Cardiovascular disease. Other factors that may put you at risk for cardiovascular disease are Sleep Apnea, stress, and frequent alcohol consumption.

Smoking

Smoking is one of the greatest risk factors for developing cardiovascular disease. In fact smoking carries a 2 to 3 fold increased risk of dying as a result of developing Cardiovascular disease. Smoking can cause heart attack, stroke, peripheral artery disease, and abdominal aortic aneurysm.

Smoking damages the endothelial cells that line the inside of blood vessels, which not only weakens the vessel, but primes it for atherosclerotic plaque development. The effects of cigarette smoke are mediated through the action of nicotine, carbon dioxide, and oxidant gases:

Nicotine

Nicotine causes myocardial ischemia, a condition in which not enough blood gets to the heart. Inadequate perfusion of the heart also means that there is also a lack of oxygen. Nicotine does this by binding to cholinergic receptors in the brain which stimulates the release of catecholamines that increase heart rate, blood pressure, and heart contractility. This increases the demand for oxygen by the heart. However, nicotine also causes vasoconstriction which reduces blood flow and thus decreases the supply of oxygen to the heart.

Carbon Monoxide

Carbon Monoxide also causes myocardial ischemia. Carbon monoxide binds more strongly to hemoglobin than oxygen, thereby preventing the oxygenation of blood. This causes hypercoagualtion as the blood thicken due to an increase in the amount of red blood cells, in an attempt to compensate for the low blood oxygen.

Oxidant Gases

Free radicals such as Nitrogen oxides and reactive oxygen species cause oxidative stress which leads to platelet activation and an increase in prothrombotic factors. Additionally free radicals play a role in the development of insulin resistance by causing inflammation. This means that smoking also increases the risk of developing Type 2 Diabetes, another risk factor for the development of cardiovascular disease.

Overweight/Obese

The rate of obesity has drastically increased since the 1980s. Obesity is an independent risk factor, as well as a contributor for other risk factors that are associated with the development of Cardiovascular Disease.

Inflammation and Insulin resistance

Excess intake of dietary fats can produce an inflammatory state within the body that is associated with insulin resistance and other deleterious effects on the cardiovascular system. Dietary fatty acids are stored in adipose tissue. When too many calories are consumed on a continuous basis, the adipose tissue becomes saturated and lipids begin to accumulate in other parts of the body that don’t normal carry a lot of fat, such as, in muscle tissue, under the skin, and  worst of all in the viscera. Visceral fat is abnormal fat, located within the main cavity of the body in which the vital organs and intestines reside. Unlike normal fat tissue, this accumulated adipose tissue begins to functions as an endocrine organ, and releases inflammatory cytokines that promote coronary artery disease (atherosclerosis).

In addition, excess adipose tissue requires more blood supply, but as body fat increases perfusion of blood into the tissue goes down. Decreased perfusion means decreased levels of oxygen within adipose tissue, and cellular hypoxia, oxidative stress, and necrosis of fat cells. As a result, there is an influx of phagocytic immune cells, such as macrophages, to clear the necrotic debris. Unfortunately, these macrophage also release inflammatory cytokines. Normally, resident macrophages are protective, and produce anti-inflammatory factors. However when there is excess adipose there is a shift in the metabolic dynamics, in which anti-inflammatory macrophage become outnumbered by inflammatory macrophages, leading again to an inflammatory state.  This chronic inflammation is what triggers insulin resistance.

Insulin resistance is when the presence of insulin no longer stimulates glucose uptake. As weight goes up, the sensitivity of muscle tissue to respond to insulin decreases. This is likely due to the increase in free fatty acids and their metabolites, which interfere with insulin signal transmission. As a result more insulin is secreted in an attempt to maintain normal glucose levels. Excessive insulin may in turn cause an increase in triglyceride levels and blood pressure. Insulin resistance is a precursor of Type 2 Diabetes

Structural & Functional Abnormalities

Obesity also causes structural and functional changes to the body, as elements of the cardiovascular system try to adapt to the burden of excess adipose tissue. Cardiac output and blood volume increase, which puts a burden on the cardiovascular system and causes enlargement of the ventricular chambers of the heart. The amount of fat on the surface of the heart closest to the aortic artery increases, so does the amount of fat within and between the muscle cells in the heart. Accumulation of fat between muscle fibers causes them degenerate. When this happens, the ability of the heart to contract is compromised.

Fat distribution matters

Having too much body fat is associated with metabolic dysfunction. Body mass index is used to measure body fat based on weight and height. A BMI over 24.9 indicates being overweight and a BMI of 30 or more indicates obesity, but not all overweight or obese persons have Insulin resistance or Cardiovascular disease. How excess fat is distributed and where it is stored in the body, play a significant role in the risk  for developing these conditions. Having a large circumference, particularly when the waist-to-hip ratio is high signifies the greatest risk. Excess fat within the abdominal cavity, or visceral fat, is a more accurate indicator for the development of Insulin Resistance and Cardiovascular disease than body mass index (BMI) alone.

Type 2 Diabetes – Glucotoxicity & Heart Disease

Diabetes is another major risk factor for Cardiovascular disease. Over 80 percent of deaths in people with Diabetes are due to Cardiovascular disease. Diabetes impairs cardiac function by disrupting the balance between pro-oxidants and antioxidants at the cellular level. This is primarily a result of hyperglycemia—glucotoxicity caused by having chronically high levels of sugar in the blood. In fact, hyperglycemia individuals suffer more severe coronary artery disease than their non-diabetic counterparts.

In a similar manner to the free fatty acids in obesity, excess circulating glucose triggers inflammation via oxidative stress. Antioxidant/pro-oxidant imbalance generates reactive oxygen species (ROS) which injure cells critical to the proper function of the heart. Oxidative damage to heart muscle cells, fibroblasts, and endothelial cells lining vessel walls cause abnormal changes to the cardiovascular system which increase the risk for hypertension and atherosclerosis. Even when there is no coronary artery disease, Diabetes can cause cardiac muscle dysfunction. Continuous generation of ROS leads to chronic inflammation, as ROS act as signal transduction molecules which stimulate the release of inflammatory cytokines and pro-coagulant factors from immune cells recruited to the site of injury.

Type 2 Diabetes is also called noninsulin-dependent diabetes, because there is a resistance to insulin. Therefore, it cannot be treated with insulin, and diet and exercise are required for its management. Type 2 Diabetes is a consequence obesity and  Metabolic Syndrome, which includes insulin resistance.

Conclusion- a balanced diet is essential.

Cardiovascular disease is the leading cause of death in adults in developed countries, and is increasing in prevalence alongside obesity. The best way to prevent cardiovascular disease is to not smoke, increase physical activity, lose weight if overweight or obese, manage high blood pressure, and control or prevent Type-2 Diabetes.

Eating a “heart healthy diet” helps to protect the cardiovascular system from oxidative stress caused by the production of reactive oxygen species generated from excess free fatty acids and glucose.  As such red meat, sugary beverages, and refined carbohydrates should be limited. While it is important to decrease intake of cholesterol, trans fats, and saturated fats, some fats are healthy.  For example, Omega-3 fatty acids, which are found in fish, are recommended as part of a “heart healthy” diet. Omeg-3 fatty acids help prevent blood clots and reduce the risk of heart attacks. To avoid the unhealthy fats, protein should be obtained from lean meats, nuts, and reduced-fat or fat-free milk.

Fruits and vegetables are essential as they are a good source of fiber. Fiber in the diet should be increased, as it hinders the absorption of cholesterol. In addition to fruits and vegetables, fiber can be found in whole grains and legumes. There are also compounds in fruits and vegetables known as Stanols that mimic the action of fiber in reducing the uptake of cholesterol by the body. It should also be noted that dairy products, particularly fermented ones, are cardio-protective.

A healthy diet, that is protective of the heart, includes physical activity and weight management. While diet contributes to disease in humans, it should be understood that the body requires energy to function properly. Food is the source of that energy, and it is only when caloric intake outweighs the amount of calories burned that fat accumulates and weight is gained. Excess body fat or weight is directly linked to metabolic syndrome, which includes insulin resistance, a precursor of Diabetes. Portion size and total caloric intake is more important than the individual foods that are eaten or not eaten. It is also important to note that salt and alcohol consumption should be limited.